while ((len = fis.read(buf)) > 0) {
            for (int i = 0; i < len; i++) {
                buf[i] ^= pwByte[p]; //重点是这句话
                if (p != pwLen)
                    p++;
                else
                    p = 0;
            }
            bos.write(buf, 0, len);
        }